This invention relates to a control system for preventing an excessive temperature rise within the heating flues of a battery of coke ovens. More particularly, the control system is designed to adjust the quantity of gas and determine the length of coking time so as to obtain constant flue temperatures over a relatively long period of time without subjecting the brickwork to excessively high operating temperatures.
Developments and effort directed toward increasing the coking capacity of a battery of coke ovens have frequently resulted in an increased temperature of the heating flues such that the maximum temperatures occurring during operation of the battery of coke ovens no longer lies to any great extent below the temperature at which the bricks become softened. Therefore, to insure that the temperature of the heating flues does not rise above an acceptable value, special care must be taken. This is usually achieved by measuring the nozzle brick temperatures in the individual heating flues at short time intervals by observations taken from the oven roof. Such measurements, of course, depend upon the reliability and skill of operators which are assigned the task of taking the temperature measurements.
Methods are already known in the art to protect and avoid the overheating of the battery of coke ovens by measuring in the individual heating flues, the temperature of either the nozzle brick or the flue gas at the top of the reversal zone. The temperature measurement is then fed to a controller which is used to control any one of the values or operating parameters which determine the amount of heat absorbed by the battery, for example, the flue gas flow pressure.
An important influence on the heating flue temperature in the battery of coke ovens is the cycle during which the oven chambers are successively pushed and which should be kept constant as far as possible. However, irregularities invariably occur in the charging and pushing of the oven chambers due to disturbances or malfunctions of the operating equipment for the battery of coke ovens. If the coking time of any given oven chamber is extended very much longer than the normal coking time as a result of such disturbances or malfunctions, then the temperatures in the adjacent heating walls to an oven chamber will after some time exceed those values which are still acceptable in view of the properties of the refractory brick material. Therefore, in the event of malfunctions causing disturbances to the coke pushing sequence, the gas supply must be throttled in the heating walls adjacent the associated ovens or, alternatively, other steps must be taken to prevent the temperatures in these heating walls from exceeding certain maximum values. It is a tenuous matter to have to rely on the skill of operating personnel to take such steps which are required immediately, particularly since the operating personnel are, of course, more likely to omit carrying out the steps required to prevent overheating of the individual flues when disturbances or malfunctions of the type indicated occur.